摘要:
A valve operating device for use in an internal combustion engine for varying operating characteristics of a pair of engine valves (20) in multi-stages depending upon operating conditions of the engine. A cam shaft (31) is provided with a high-speed cam (32), a pair of medium-speed cams disposed on opposite sides of the high-speed cam (32), and a pair of low-speed cams (34) disposed between the medium-speed cams (33) and the high-speed cam (32). A rocker shaft (35) is provided with a first free rocker arm (36) in sliding contact with the high-speed cam (32), a pair of driving rocker arms (37) operatively connected to the pair of engine valves (20), respectively, and in sliding contact with the low-speed cams (34), and a pair of second free rocker arms (38) disposed with the driving rocker arms (37) interposed between the second free rocker arms (38) and the first free rocker arm (36) to be in sliding contact with the medium-speed cams (33). First and second connection switching means (39, 40) are provided and separately switchable between states for selectively connecting the various rocker arms for operating the driving rocker arms (37) and engine valves (20) in low-speed, medium-speed and high-speed operating ranges of the engine.
摘要:
A valve-operation control system for an internal combustion engine includes a timing transmitting device for transmitting the rotational power of a crankshaft at a speed reduction ratio of 1/4 to a cam shaft, and intake-side and exhaust-side valve operating devices. Each of the valve operating device includes a first cam provided on the cam shaft and having a single cam lobe protruding outwardly with a valve-opening profile suitable for an extremely low-speed operation of the engine, a second cam provided on the cam shaft and having a pair of cam lobes provided at locations circumferentially spaced apart through 180 degrees to protrude outwardly with an opening profile suitable for a low-speed operational state of the engine, a third cam provided on the cam shaft and having a pair of cam lobes provided at locations circumferentially spaced apart through 180 degrees to protrude outwardly with an opening profile suitable for a high-speed operational state of the engine, with first, second and third rocker arms following the first, second and third cams, respectively. A connection switchover device is provided in the first, second and third rocker arms for switching the selective connection and disconnection of the rocker arms in accordance with the operational state of the engine. The first rocker arm is operatively connected to the intake or exhaust valves for operation of the valves in an 8-cycle mode to inhibit the discharge of a harmful hydrocarbons at an extremely slow speed of the engine.
摘要:
A method for producing D-lactic acid in high yield, and to provide a method for producing D-lactic acid with high selectivity, in which optical purity is high and a by-product organic acid is small. In one aspect, a microorganism, wherein activity of pyruvate formate-lyase (pfl) is inactivated or decreased, and further activity of Escherichia coli-derived NADH-dependent D-lactate dehydrogenase (ldhA) is enhanced, is cultured to efficiently produce D-lactic acid. With regard to a method for enhancing ldhA activity, by linking, on a genome, a gene encoding ldhA with a promoter of a gene which controls expression of a protein involved in a glycolytic pathway, a nucleic acid biosynthesis pathway or an amino acid biosynthesis pathway, suitable results are obtained compared to the method for enhancing expression of the gene using an expression vector. A microorganism in which a dld gene is substantially inactivated or decreased is cultured to produce high quality D-lactic acid with reduced concentration of pyruvic acid.
摘要:
A novel gluconate dehydratase derived from Achromobacter xylosoxidans and a gene encoding the gluconate dehydratase are provided. By reacting the gluconate dehydratase or a transformed cell containing the gene with an aldonic acid, the corresponding 2-keto-3-deoxyaldonic acid can be efficiently produced.
摘要:
A method for casting a rocker arm made of light alloy for use in an overhead cam shaft type valve operating mechanism of an internal combustion engine, which rocker arm includes a thick-walled bearing section to be fitted on a rocker arm shaft and is integrally provided with a wear-resistive piece having a protrusion on its rear surface and adapted to abut a cam. After molten metal has been injected under pressure into a metallic mold for the rocker arm, a secondary pressurizing force directed in the direction of an imaginary center axis of a rocker arm shaft is exerted by means of a pressurizing rod. In the metallic mold for the rocker arm, a sprue is provided close to the position where the wear-resistive piece is disposed with respect to the position where the bearing section is formed, and the direction of the sprue is directed towards the position where the wear-resistive place is disposed.
摘要:
An SOHC type internal combustion engine having a cam shaft for opening and closing intake and exhaust valves via rocker arms, the cam shaft being held between a cam shaft receiving wall of a cylinder head and a cam shaft holder which is secured to the cam shaft receiving wall, wherein a hole for allowing insertion of an ignition plug into a plug mounting hole is formed in the cam shaft receiving wall and opens to the surface of the wall against which a cam shaft holder abuts, and a hole for guiding a high power cord for an ignition plug is formed between the mutually abutting surfaces of the cam shaft receiving wall and the cam shaft holder.
摘要:
A spark plug cap apparatus for an internal combustion engine having relatively deep and generally vertical spark plug receiving bores. The upper end of the bore is provided with an annular protrusion. A resilient head cover has a bent flange for extending over and sealably engaging the annular protrusion. The head cover has a downwardly extending seal lip for engaging the inside of the bore. A pipe is molded to the head cover and extends downwardly to engage the top of the spark plug. The spark wire extends through the head cover and pipe. A vent hole is provided in the head cover.
摘要:
A novel gluconate dehydratase derived from Achromobacter xylosoxidans and a gene encoding the gluconate dehydratase are provided. By reacting the gluconate dehydratase or a transformed cell containing the gene with an aldonic acid, the corresponding 2-keto-3-deoxyaldonic acid can be efficiently produced.
摘要:
A valve operating system in an internal combustion engine includes a cam shaft provided with a plurality of valve operating cams, a plurality of rocker arms positioned adjacent one another, an associative operation switch capable of being switched between a state in which it permits the rocker arms adjacent each other to be operated associatively with each other, and a state in which it releases the associative operation. An urging means for urging the free rocker arm of the plurality of rocker arms toward the valve operating cam corresponding to the free rocker arm, which becomes free relative to an engine valve, when the associative operation switch is brought into the associative operation releasing state. The free rocker arm is provided with first and second support walls spaced apart and opposed to each other, and a roller is provided in rolling contact with a valve operating cam corresponding to the free rocker arm, and is rollably supported on a support shaft mounted to extend between the support walls through a bearing. In such valve operating system, one of the support walls included in the free rocker arm is integrally provided with a receiving portion which contacts with the urging means. Therefore, the structure of the free rocker arm can be simplified in such a manner that the receiving portion is positioned to the side of the roller. In addition, an increase in size of the free rocker arm can be avoided, and the inertial weight is reduced. Thus, it is possible to conveniently accommodate the high-speed rotation of the internal combustion engine.
摘要:
Optically active chroman-3-acetic acids and optically active chroman-3-acetic acid esters can be obtained by treating a mixture of (3R)- and (3S)-chroman-3-acetic esters of formula (I) ##STR1## [wherein R.sub.1 is a straight or branched alkyl group having 1-5 carbon atoms and R.sub.2 is a hydrogen atom or substituted or unsubstituted amino group]is treated with an esterase which has an optically selective hydrolyzing activity or microorganisms which carry said hydrolase, or a preparation therefrom. A novel esterase derived from bacteria of genus Pseudonocardia can also be used as said esterase.